Torque motor driven direct drive valves are well known in the art including those which operate through the utilization of a rotary torque motor having a drive member extending from the rotor thereof into contact with a hydraulic valve to directly move the valve to thereby control the flow of fluid from a source thereof to a load in response to electrical signals applied to the drive motor. Such direct drive valves are very time consuming to manufacture because the precise positioning of the stator, rotor, the position feed back device, rotor stops and the valve flow control components in relationship to each other is required to achieve optimum performance and is extremely complex. If a particular hydraulic component of the valve portion of the direct drive valve is changed because of a particular application, added extensive costs are incurred. This results because a complete disassembly and reassembly of all of the motor components is usually required.
Typical of such prior art direct drive servovalves is that illustrated in U.S. Pat. No. 4,793,377, the disclosure of which is incorporated herein by this reference. Other prior art known to applicant which also includes direct drive valves of the type above referred to is U.S. Pat. Nos. 4,197,474; 2,769,943; 2,697,016; 4,452,423; 4,339,737 and 4,702,123 as well as Canadian Patent No. 601808 issued Jul. 19, 1960 and United Kingdom Patent No. 1521668 issued Aug. 16, 1978.
Although the prior art direct drive servovalves disclosed in each of these references function quite well for the purposes intended, they nonetheless suffer from the limitations as above set forth and are therefore complex and relatively expensive to assemble or to repair. In addition to all of the foregoing difficulties, particular attention must be given to linear spacing and concentricities of rotating parts and bearings to ensure a smooth and optimum performance for the direct drive servovalve.